Clearly a 30-year-old PR representative for Somerfield Stores in the UK didn't know and was one of the quarter of the population about whom she was writing. From the Times On-Line,
“ Brits will on average be enjoying over 3.5 eggs each over the Easter weekend alone. But over a quarter don’t know why handing them out symbolises the birth of Jesus. . . .” Press release from Somerfield, April 3[h/t to King Banaian]
“ Brits will on average be enjoying over 3.5 eggs each over the Easter weekend alone. But over a quarter don’t know why handing them out symbolises the rebirth of Jesus . . .” Revised press release
“ Brits will on average be enjoying over 3.5 eggs each over the Easter weekend alone. But over a quarter don’t know why handing them out symbolises the resurrection of Jesus” Second revision
[emphasis added]